All other entities that are part of the Bitcoin ecosystem can easily and quickly move onto various altcoins and/or other business ventures.
I would disagree with this.
People who have invested into bitcoin as a store of value or have built their business around bitcoin have a vested interest as well.
Just because a miner has a more difficult time moving on to another business venture etc does not mean that they are the only ones.
One could argue that a bitcoin miner could sell off their equipment/assets and move on to other ventures/alt-coins/etc.
Not really an absolute type of statement I would agree with there.
I think it is fairly trivial for the majority of Bitcoin related businesses to either diversify into altcoins or outright change to an altcoin company. For example, most exchanges have diversified into altcoin trading. Your own business has diversified into physical coins loaded with XMR, and I suspect would continue doing well with other altcoins. I believe that most Bitcoin related businesses are more of a pro-crypto bet than a pro-Bitcoin bet.
Long term holders of Bitcoin have more of a vested interest, however liquidity for Bitcoin is much greater than liquidity for Bitcoin miners, so unless you are the largest of the large holders, you can probably sell what you own with little slippage.